<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
	<style>
		.fu{
			background-color: #ff0;
			overflow: hidden;
		}
		.fu>div{
            width: 100px;
            height: 100px;
			border: 3px solid #000;
		}
		.z1{
			background-color: #f00;
			float: left;
		}
		.z2{
			background-color: #0f0;
			float: left;
		}
		.z3{
			background-color: #00f;
			float: left;
		}
	</style>
</head>
<body>
<div class="fu">
	<div class="z1"></div>
	<div class="z2"></div>
	<div class="z3"></div>
</div>
</body>
</html>